Surfactants, such as Betaines, amine oxides and quaternaries (from C.sub.6 -C.sub.22) have been used on a commercial basis in the cosmetic, toiletry and personal care industry for the past 40 years primarily as surfactants for their mildness and lack of irritation on a commercial basis. The aforementioned surfactants have been prepared from natural oils, such as coconut oil, palm kernal oil, soybean oil, safflower seed oil, corn oil, etc. The oils are reacted with amine derivatives such as dimethylaminopropylamine, diethylaminopropyl amine, etc. via transamidation with caustic catalysts to yield the linear C.sub.6 through C.sub.22 dimethylaminopropyl amine derivatives. Similarly, linear fatty acids ranging from C.sub.6 through C.sub.22 have been reacted to form the linear tertiary amine salts which upon application of heat drove off water to form the corresponding C.sub.6 through C.sub.22 linear dimethylaminopropylamine derivative. Aromatic acids such as benzoic acid as well as branched acids similarly have been reacted to form the resultant aromatic dimethylamidopropyl amine or iso-dimethylamido propylamine which could serve as a building block for the betaine. However, aromatic backboned surfactants have not found wide commercial use.
Over the years, betaines, amine oxides and quaternaries have become commodity products used in a wide array of applications ranging from shampoos, nonirritating baby shampoos, liquid soaps, dish detergents (to preclude introduction of phosphate builders), body scrubs, shaving creams, etc. When the pH of a cosmetic or toiletry product incorporating betaines is dropped to a pH slightly below about 7.0, the betaine becomes mildly cationic and improved feel and combability of hair results. When coupled with amine oxides, the combination yields a high degree of hair detangling characteristics in shampoos.
The inclusion of betaines and amine oxides into liquid soaps in combination with alpha olefin sulfonates and amides ranging in size from C.sub.12 -C.sub.18 at a pH under 7.0, effectively functions as a thickening agent in a liquid soap which leaves the hands soft and silky. Betaines with a preponderance of C.sub.12 through C.sub.14 groups have been shown to be effective foaming agents when used in combination with sodium lauryl sulfate, sodium lauryl ether sulfates and alpha olefin sulfonates.
Betaines as well as amine oxides with chain lengths ranging from C.sub.16 through C.sub.22 exhibit special effectiveness as thickening and conditioning agents. The introduction of a betaine of dimethyl oleyl betaine into a shampoo or body lotion does little to promote foam; however, viscosity of a resultant formulation with up to 2.0 percent of higher molecular weight chains such as oleyl, erucyl, arachidyl give significant thickening.
Betaines, amine oxides and quaternaries have been found to be extremely effective as tartar-removing agents in toothpaste formulations. A great deal of work had been done in this research arena in the early '70s. When betaines were introduced into toothpaste formulations, teeth were found to be "squeaky clean". However, a major drawback in using these compositions was the taste which was very difficult to mask with flavors. Consequently, as a result of this foul taste, no major brands of toothpaste were introduced to the marketplace. Numerous betaine derivatives were made but were never commercialized.
Betaines have also demonstrated properties of corrosion inhibition and have been incorporated into industrial formulations. The lower molecular weight betaines ranging from C.sub.6 through C.sub.18 have found wide use in industrial applications.
Another area in which betaines and amine oxides have been used in large volume with considerable success is in the oil and oil-field-related industry. As surfactants in the oil industry, betaines and amine oxides are used as emulsifiers, wetting agents, antifoulants, cleaners and detergents. With respect to paraffinic chemicals, betaines are used as surfactants for breaking up emulsions and as defoamers, for cleaning tanks, dispersing paraffins and as wetting agents for paraffinies. Betaines are also used in aqueous-isopropanol solutions to improve water injectivity in water flooding, as corrosion preventatives in floods, as a surfactant for clarification in water containing H.sub.2 S, to assist in the control of fouling due to microbial action, to enhance scale inhibition and also as an emulsifier and coupler in oil well formulations.
With the fairly recent concern with nitrosoamines which may be present as minor contaminants in widely used diethanolamide amines (derived from fatty acids as well as methyl esters), betaines and amine oxides have become used in extremely large quantities in consumer products such as shampoos, body baths, liquid soaps, etc.